Foss' accountant, Richard Seidel, has been beta testing the service on his home phone for about three months now. He said he's noticed a "significant reduction" in the number of robocalls.

"It's really a time-saver," Seidel told me. "These calls are a real pain and it's really a waste of time when you get interrupted by them."

Source: Aaron Foss

Software developer Aaron Foss, who won the FTC'S RoboCall Challenge in April, plans to offer a free blocking service soon.

Foss has been working full time on this service since April, when he tied for first place and won $25,000 in the Federal Trade Commission's Robocall Challenge.

"We're aware and extremely pleased that potential technological solutions to help consumers block unwanted, illegal robocalls are making their way to the marketplace," said Jessica Rich, director of the FTC's Bureau of Consumer Protection.

Service will roll out over time

Nomorobo is currently available to people who have VoiP service with AT&T U-verse, Cablevision Optimum, SureWest, Verizon FiOS and Vonage. Foss started with these companies because they make it easy for people to get the simultaneous ring feature. He hopes to add traditional landline phone companies in the near future.

Nomorobo's algorithm uses caller ID and call frequency information to screen incoming calls. For now, it's using a database of 1.2 million phone numbers from complaints filed with state and federal regulators. Going forward, calls coming to subscribers will be added.

"My hat is off to Mr. Foss," said Kevin Rupy, senior director of law and policy at USTelecom, a trade group that represents phone service providers. "We support development of consumer-centric solutions to this problem ... but this is an extremely complex, technologically challenging issue to address."

Rupy noted that simultaneous ring is not available from all phone companies and he worries that it might be relatively easy for robocallers to defeat a system based on caller ID. For example, it's easy to spot 5,000 calls coming from one phone number, but what if these phone spammers make 5,000 calls from 5,000 different numbers?

"This is a technological arms race," Rupy said. "Sometimes when you build a better mousetrap, you get a better mouse."

Foss agrees that this is a first-generation product that might not work in the future.

"If the robocallers adapt, then I'll have to adapt," he told me.

John Breyault with Fraud.org, a website run by the National Consumers League (NCL), points out that most illegal robocalls are from scammers who are trying to defraud consumers.

"They don't respect the federal Do Not Call Registry, and since they're often outside the country, they're hard to prosecute," he said.

While NCL doesn't endorse products, Breyault is happy to see technology used to help consumers fight back against the bad guys.

This is not the only solution to robocalls. Other software and hardware products are being developed. Foss said he welcomes the competition.

"The more products that are out there to stop these calls and protect people from these scams, the better it is for everyone."